The instant invention relates to a process for the control of a yarn storage mechanism, as well as to a spinning device incorporating the process. In particular, when conical bobbins are wound, e.g. on open-end rotor spinning machines, the problem exists that the yarn which is delivered at a constant speed cannot be wound up at constant speed by the winding mechanism on a cross-wound bobbin. As is known, the cause for this is that conical bobbins rotate at a constant speed but have different circumferential lengths because of their conicity. To solve this problem, the state of the art has proposed to use yarn storage mechanisms which ensure that yarn which cannot be wound up at the moment is placed in intermediate storage, this yarn storage being filled to a maximum when the yarn guide deposits the yarn in the area of the smaller diameter of the conical bobbin. The yarn storage contains the shortest yarn loop when the yarn guide deposits yarn in the area of the larger diameter of the conical bobbin. DE 38 06 139 A1 proposes for example to make the yarn storage mechanism in the form of a swivelling lever which is positively controlled as a function of the movement of the yarn guide. Similarly, to control jigging of the yarn guides, a jigging rod extending over the spinning machine is provided for this. The yarn is taken from the yarn storage mechanism and is formed into a loop at a right angle to its direction of movement, whereby this loop can be enlarged or reduced as required by the swivelling lever.
DE-A 24 54 916 discloses a winding mechanism for conical cross-wound bobbins whereby a yarn storage mechanism is provided to receive the periodically produced excess yarn, the yarn storage mechanism being made in the form of a spring-loaded compensator arm which deflects the yarn at a right angle to the direction of yarn movement and holds it under tension. Under the influence of the spring, the size of the yarn loop increases automatically when more yarn is delivered than is wound up. Inversely, the yarn storage mechanism is able to dispense yarn when needed. The yarn loop is not subjected to positive control.
A similar yarn storage mechanism is known from the rotor spinning machine RU 14 of Schubert & Salzer Maschinenfabrik Aktiengesellschaft in D 8070 Ingolstadt, in which the compensator arm deflects the yarn at a right angle to the bobbin axis in direction of the interior of the machine. The force acting upon the compensator arm can be adjusted by means of an adjusting mechanism so that bobbins with different yarn tensions can be produced at the winding station. Such yarn storage mechanisms are not only used for the winding of conical bobbins, but also if the yarn is paraffined at the same time, for example, as it is wound up. The irregularities which then occur in the yarn tension are compensated for by the yarn storage mechanism.
The known yarn storage mechanisms have the disadvantage that contact between compensator arm and yarn is not always ensured beyond the operating range of the compensator arm when yarn tension changes or when the yarn loop becomes smaller. When the compensator arm is moved rapidly in direction of its end position within its operating range as the yarn tension increases, it may occur that the compensator arm detaches itself from the yarn and is then brought back suddenly towards it under the force of the spring. This may cause yarn breakage.